Advanced Materials Research Vols. 807-809

Abstract: Modification of (Mg_0.95Co_0.05)TiO₃ ceramics by Ca_0.61Nd_0.78/3TiO₃ addition was investigated. The Ca_0.61Nd_0.78/3TiO₃ content plays a significant role in improving the dielectric properties. Microwave dielectric measurement showed an increase in dielectric constant (εr) and temperature coefficient of the resonant frequency (τf) and a decrease in Q value with increasing Ca_0.61Nd_0.78/3TiO₃ content. By properly adjusting the Ca_0.61Nd_0.78/3TiO₃ content, zero temperature coefficient of resonate frequencyτfcan also be obtained. It becomes more promising in the application of wireless system.At 1375°C, the 0.85(Mg_0.95Co_0.05)TiO₃-0.15Ca_0.61Nd_0.78/3TiO₃ ceramics possesses excellent microwave dielectric properties: a dielectric constant εr of 24.37, a Qf value of 66200 ( at 7 GHz ) and a τf value of-1.4 ppm/°C.

Abstract: LaNi₅-xwt%Mg hydrogen storage alloys with different Mg content were made from pure La, Mg and Ni metal powder by mechanical alloying, selecting appropriate ball-milling parameters in 0.4MPa hydrogen atmosphere. The characterizations for hydrogen storage alloy show that a multi-phase alloy composed of MgH₂, LaH₃, Mg₂NiH₄ and Ni was obtained, the alloy have two hydrogen desorption temperature range, and the alloy with 25wt% Mg content can desorb hydrogen up to 4.02wt%.

Abstract: This paper studied the preparation method of the multi-walled carbon ITO nanotubes electrode, which was prepared by ITO electrode self-assembled after adsorbing n-Dodecanethiol.The multi-walled carbon ITO nanotubes electrode was prepared by self-assembled after adsorbed n-Dodecanethiol.The electrode was characterized with DA as the representative. The effects on electrochemical behavior of NaOH treatment and pH were discussed. The results showed that after NaOH treatment increased the electrocatalysis to DA. The electrode was used for detection of DA in the 1×10^-5 mol/L ascorbic acid (AA) in the presence DA. The linear range was 1×10^-8~1.5×10^-7 mol/L, the detection limit was 5.0×10^-9 mol/L. It could effectively removed the disturb of AA.

Abstract: Several kinds of rubbers used for fabric expansion joints were studied by Thermogravimetric analysis under inert atmosphere before and after artificial accelerated thermal aging. The results showed that because of the difference of the chemical structures, the rubber aging is different. And the thermal stability of Polytetrafluoroethylene (PTFE) was obviously higher than that of other two kinds of rubbers, ethylene-propylene-diene-terpolymer rubber (EPDM) and fluororubber.

Abstract: Microstructural evolution of a nickel-base directionally solidified superalloy during thermal fatigue was investigated. Three kinds of phase transformation have been observed: μ phase precipitated due to the relatively increasing of the concentration of forming μ phase elements as a result of the depletion of Al and Cr; Script-like carbides and γ phase dissolved into the matrix. Also, thermal fatigue was strongly influenced by oxidation.

Abstract: A 6061 aluminium rectangular tube extrusion using porthole dies was simulated by finite element software DEFORM-3D. The speed, stress, strain and temperature in the extrusion was given and analyzed. Using the original porthole die, the speed at the bearing entrance is not uniform. Bearing length at the rectangular corners should be increased. The stress, strain and temperature near the bearing are the largest, so the region of the die should be treated and enhanced.

Abstract: The corrosion rates of rebar HRB335 and the tensile mechanical properties before and after corrosion in 1.5 wt.% NaCl solution were studied. The results showed that, with increasing corrosion time from 30 days to 90 days, the corrosion rate of rebar HRB335 increases. With increasing corrosion time (corrosion rate), the yield strength and tensile strength of rebar HRB335 decrease, but the elongation increases at first and then decreases.

Abstract: The corrosion rates and the tensile mechanical properties of rebar HRB400after corrosion in 1.5 wt.% NaCl solution were studied. The results showed that, with the increase of corrosion time, the corrosion rate of rebar HRB400 increases. Meanwhile, the yield strength and tensile strength decrease, but the elongation increases at first and then decreases.

Abstract: The photocatalytic degradation process of waste water was usually influenced by many factors, such as different ions, addition reagent and pH value. In order to investigate the effect of ions strength in the photocatalytic process, the anions and cations were systematically investigated with P25 TiO₂ photocatalyst with Rhodamine B (RB) as waste water in this work. The results showed that the cations of low valence showed minimum negative effect on degradation rate and the most anions showed enhance the degradation rate of RB. The ions strength showed random in the photocatalytic process.

Abstract: The compare of distribution and morphology for the pores in the CFRP laminates and the corner of L-shape CFRP components is analyzed, and the conclusions are as follows. The pores in the corner of L-shape CFRP components and CFRP laminates are all spherical or ellipsoidal and the sizes are small when the porosity is small. As the porosity increases, the pores in the laminates become elongated type, while the pores in the corners become centralized. When the porosity is further increased, irregular pores in the fiber bundle of the corners appear, and the tenuous pores in interlayer of the laminates appear. The average porosity of the corners is smaller than that of laminates in general. The length, width and area of the pores both in the corners and laminates increase as the porosity increases. The length variation of the corners is less than that of laminates, and the width variation of the corners is larger than that of laminates. With the porosity increases, the pore width to length ratio both of the corners and laminates decreases. When compared to laminates, the change range of the ratio for the corners is little. The pore morphology and ultrasonic attenuation exists corresponding relationship.